Proxy Re-Encryption (PRE) is a system that delegates the decryption authority of a ciphertext to others without decrypting the ciphertext. Non-Patent Literature 1 includes a description on an Identity-Based PRE (IBPRE) scheme. Non-Patent Literature 2 includes a description on an Attribute-Based PRE (ABPRE) scheme. In the PRE scheme described in Non-Patent Literature 2, only an attribute constituted of an AND operation and negation can be designated to a ciphertext.
Non-Patent Literature 3 includes a description on a conditional proxy re-encryption (CPRE) scheme that can designate a condition for re-encryption.
Patent Literature 1 includes a description on a functional encryption (FE) scheme. Non-Patent Literature 4 includes a description on the FPRE scheme.